The group of organisms referred to as algae is one of the most prolific and widespread on earth. Over 150,000 species of algae are currently known, and it is certain that more remain to be discovered. Of this large number of species, only a relative handful has been studied in detail. All that is known about the majority of algae species is their name and basic identifying characteristics and qualities. In fact, there is even some uncertainty about how to classify all the different algae species in the overall taxonomy of life.
What is known is that algae (including plant-like forms of many different sizes and colors, diatoms, and cyanobacteria) constitute one of the most important types of life on earth, responsible for most of our atmosphere as well as forming the basis of the food chain for many other forms of life. Entire ecosystems have evolved around algae or symbiotically with algae, and the algal environment includes food sources, predators, viruses, and many other environmental elements that we typically associate with higher forms of life.
Despite the extent and importance of algae, direct human use has been limited. Algae are grown or harvested as food, especially in Asia and often in the form of “seaweed.” They are also widely used to produce various ingredients such as colorants and food additives. Algae are used in the treatment of municipal waste streams, and in industrial processes to concentrate and remove heavy metal contamination. Fossil forms known as diatomaceous earth are used as a filtration medium and for other applications.
An application of algae which has begun to emerge in recent years is as a source of fuel. It is known that algae can produce oil, starch, and gas, which can be used in production of diesel fuel, alcohol (e.g. ethanol), and hydrogen or methane gas.
While other biological materials can also yield these fuels, what distinguishes algae are their high productivity and theoretical low cost. Algae can grow from 10 to 100 times as fast as other forms of plants, and can grow well under a wide range of temperature, water quality, and nutrient conditions. Algae can also be highly prolific in their production of desired oils or starches, in some cases producing as much as 60% of their own weight in these forms. Moreover, algae achieve all this with the most basic of inputs, needing only sunlight, water, air, and simple nutrients.
Despite the clear potential benefits of algae as a fuel source, actually achieving this potential has proved frustrating and difficult, for a number of reasons. For example, we do not know enough about what species among the many species of algae are the best for optimum growth under specific conditions. Further, little is known about how to grow algae in a selectable, controlled and repeatable way, or how to encourage high productivity in forming fuel-precursor materials such as oil or starch.